Chinese paramilitary policemen stand guard near Tiananmen Gate in Beijing Thursday, Nov. 1, 2012. Beijing is tightening security as its all-important Communist Party congress approaches, and some of the measures seem bizarre. Most of the security measures were implemented in time for Thursday's opening of a meeting of the Central Committee.

The Chinese authorities are tightly muzzling critics as they prepare for the ruling Communist Party’s national congress and issuing a slew of security edicts, ranging from a ban on the sale of knives in the capital to admonitions about subversive ping pong balls.

Human rights lawyers, religious activists, and political dissidents are among those exiled from their homes in Beijing or forbidden to speak publicly until the 18th party congress, due to seal a once-in-a-decade leadership change, is over.

“I was forced to leave Beijing with my parents under police supervision on Oct. 25..I am in Anhui Province,” wrote AIDS activist Hu Jia, normally under house arrest in the capital, on his blog today. He said he would not be allowed to return home until Nov. 20.

The congress will start on Nov. 8 and is expected to last about a week.

“I have just finished talking to the police,” said human rights lawyer Li Fangping, when contacted by a reporter. “It is really inconvenient for me to talk to you,” he added, before hanging up.

Liu Xiaoyuan, lawyer to prominent dissident artist Ai Weiwei, is also among those banned from Beijing for the next two weeks. Currently visiting his home province of Jiangxi on business, he said “the police came to talk to me … and told me not to return to Beijing until the end of the 18th party congress. I think it’s ridiculous.”

The Chinese security forces are always on high alert before major political events, such as significant anniversaries or important party meetings. However, the run-up to the party congress has been marked by signs of unusual nervousness.